The principle investigator, (Dr. Olson), is currently a postdoctoral fellow at the University of Iowa. He has significant experience studying bacterial physiology, biofilm production and host colonization factors. Within the next 12 months, he plans on obtaining a tenure track academic position at a major research institute with a future research focus on understanding S. aureus physiology and pathogenesis. The long-term objectives of his laboratory will be to understand the molecular mechanisms involved in S. aureus colonization. His research interests involve understanding how the staphylococci interact with each other and with the host. The main project that he is pursuing involves the characterization of a novel quorum-quenching protein that S. aureus secretes. Current work involves elucidating the mechanism by which S. aureus is able to disrupt and alter genetic function of other bacteria, specifically, S. epidermidis. Overall, the understanding polymicrobial interactions and the effects of bacteria have on each other will be used to gain insight into both human colonization and the dynamics of the human microbiome. The specific aims of this proposal are: I) determine the extent, breadth and distribution of the quorum quenching protein, SqqA; II) define the mechanism by which SqqA interferes with S. epidermidis quorum sensing; and III) assess how this polymicrobial interplay modulates the colonization state of the human host. Dr. Olson's research plan has great relevance to public health as S. aureus is a major cause of infection and death in community and hospital associated infections. Findings from the proposed project will increase understanding of S. aureus colonization mechanisms and may lead to new therapeutic options for preventing S. aureus infections.